John Schaefer - Germany/Prussia -> US abt 1900

I'm looking for information on my grandfather John (Jack) Schaefer (1891-1937) of Roseville, MI.He's thought to have immigrated with his father very early 1900s.Married Madaline Locke (1896-1971) Dec. 1915; two sons Walter B. (1916-1990) and Kenneth R. (1918-1970).